Fix RPC server threads file handle affinity to work better with ZFS.

  Instead of taking 8 specific bytes of file handle to identify file during
RPC thread affitinity handling, use trivial hash of the full file handle.
ZFS's struct zfid_short does not have padding field after the length field,
as result, originally picked 8 bytes are loosing lower 16 bits of object ID,
causing many false matches and unneeded requests affinity to same thread.
  This fix substantially improves NFS server latency and scalability in SPEC
NFS benchmark by more flexible use of multiple NFS threads.

Sponsored by:	iXsystems, Inc.

1 files changed, 11 insertions, 7 deletions

diff --git a/sys/fs/nfsserver/nfs_fha_new.c b/sys/fs/nfsserver/nfs_fha_new.c
index c05ad28..2e7115f 100644
--- a/sys/fs/nfsserver/nfs_fha_new.c
+++ b/sys/fs/nfsserver/nfs_fha_new.c
@@ -41,7 +41,7 @@ static void fhanew_init(void *foo);
 static void fhanew_uninit(void *foo);
 rpcproc_t fhanew_get_procnum(rpcproc_t procnum);
 int fhanew_realign(struct mbuf **mb, int malloc_flags);
-int fhanew_get_fh(fhandle_t *fh, int v3, struct mbuf **md, caddr_t *dpos);
+int fhanew_get_fh(uint64_t *fh, int v3, struct mbuf **md, caddr_t *dpos);
 int fhanew_is_read(rpcproc_t procnum);
 int fhanew_is_write(rpcproc_t procnum);
 int fhanew_get_offset(struct mbuf **md, caddr_t *dpos, int v3,
@@ -128,11 +128,13 @@ fhanew_realign(struct mbuf **mb, int malloc_flags)
 }
 
 int
-fhanew_get_fh(fhandle_t *fh, int v3, struct mbuf **md, caddr_t *dpos)
+fhanew_get_fh(uint64_t *fh, int v3, struct mbuf **md, caddr_t *dpos)
 {
 	struct nfsrv_descript lnd, *nd;
 	uint32_t *tl;
-	int error, len;
+	uint8_t *buf;
+	uint64_t t;
+	int error, len, i;
 
 	error = 0;
 	len = 0;
@@ -151,11 +153,13 @@ fhanew_get_fh(fhandle_t *fh, int v3, struct mbuf **md, caddr_t *dpos)
 		len = NFSX_V2FH;
 	}
 
+	t = 0;
 	if (len != 0) {
-		NFSM_DISSECT_NONBLOCK(tl, uint32_t *, len);
-		bcopy(tl, fh, len);
-	} else
-		bzero(fh, sizeof(*fh));
+		NFSM_DISSECT_NONBLOCK(buf, uint8_t *, len);
+		for (i = 0; i < len; i++)
+			t ^= ((uint64_t)buf[i] << (i & 7) * 8);
+	}
+	*fh = t;
 
 nfsmout:
 	*md = nd->nd_md;